1. Field of the Invention
The invention relates to a motor vehicle door lock including a key collar support plate fixedly attached on a support sheet, and a collar element supported on the collar support plate where, in operation, the collar element engages a lock catch of the motor vehicle door lock. More specifically, the invention relates to such key collars with an elastomer arrangement which allows the collar element to move a limited distance relative to the collar support plate in the plane of the collar support plate. In addition, the present invention also relates to motor vehicle door locks including such a key collar, a lock catch where the lock catch includes an opening that swivels around an axis to receive a leading bridge of a key collar and also includes a detent pawl which fixes the lock catch in the closed position.
2. Description of Related Art
Motor vehicle door locks are generally based on several, conventionally known designs. A key collar of a motor vehicle door lock is generally mounted on a door post or a part of the frame (for example, the B column or the C column). Usually, the key collar is mounted using mounting screws which are inserted through insertion openings provided in the side flanges of the key collar and screwed into threaded openings in the door posts. The lock housing of these motor vehicle door locks which house the various components of the door lock, may be made from one or two parts and is mounted in a similar manner using mounting screws on the corresponding body part which is generally the front plate of a motor vehicle door. For a long time, it has been assumed in the art that it is important to keep the relative positions between the key collar and lock housing constant as much as possible in order to ensure that there is always an accurately determined relative engagement position of the two parts of the motor vehicle door lock.
In key collar and motor vehicle door lock designs on which the present invention is based (German Utility Model DE-U-88 06 819), the comfort requirements of the motor vehicle user with regard to noise abatement have become important. In accordance with the prior art, the flanges of the collar element which project laterally are inserted into an elastomer arrangement in a trough-shaped collar support plate so that there is no direct contact bridge for solid-borne noise between the collar element and the collar support plate. The collar support plate itself is attached, as explained previously, to the mounting sheet with mounting screws. This embedding of the collar element in the elastomer arrangement necessarily results in allowing a limited amount of movement by the collar elements. Therefore, the collar elements may move a little to the top or bottom, to the front or back, depending on the compliance of the elastomer arrangement. This is not inherently desirable, but in view of the small deflection of less than +/-1 mm, the movement can be regarded as an acceptable compromise.
In addition, prior art key collars for motor vehicle door locks including a key support plate with a permanently deformable section is also known (German Patent DE-C-30 26 147). In this design, the collar element more or less adjusts itself in the installation of the motor vehicle door and then, may be fixedly mounted in the adjusted position by tightening the mounting screws on the support sheet. This is, of course, a much easier installation of the key collar than the prior conventional installation and readjustment designs which required repeated loosening and retightening of mounting screws (published German Patent Application DE-A-29 36 997).
A conventional lock structure with a rotary catch including a fork catch and tensile stressed detent pawl is also disclosed in the above explained prior art. The structure shown is considered to be the standard for conventional motor vehicle door locks and the prior art shows a key collar (i.e. a locking pin) located far above the swivel axis of the lock catch with only one bridge in the lock latch when the lock latch is in its closed position. This has the known effect of transferring the shearing forces during a crash through a relatively large lever arm engaging the rotary catch. Consequently, the rotary catch must be over designed and made relatively massive to increase its strength.
In addition, making a rotary catch as a disk of solid material instead of a fork catch is also known in the prior art (German Patent DE-C-16 78 121). In such designs, the rotary catch is pivotally mounted in a recess with a peripheral surface abutting the rotary catch. As a result, there is no bearing pin in the middle of the rotary catch and the swivel axis of the rotary catch is only virtual. The rotary catch is fixed axially by the bottom surface of the recess and by a cover that includes an impression in the area of the center point of the rotary catch on the cover which limits the sliding friction between the rotary catch and the cover.
Generally in the prior art, a key collar used in the motor vehicle door lock is designed to withstand large forces during a vehicle crash. This entails over dimensioning of the components and do not provide the optimum configuration for normal, everyday operation.